This application is related to Japanese patent application No. HEI 10-135885 filed on Apr. 8, 1998 whose priority is claimed under 35 USC xc2xa7119, the disclosure of which is incorporated herein by reference in its entirety.
1. Field of the Invention
The present invention relates to a support system for making decisions on medical treatment plans or test plans, and more particularly to a system for providing a support in deciding a medical treatment plan or a test plan for a person to be inspected.
2. Description of the Related Art
In clinical medicine, selection from a variety of treatment plans or test plans must often be made in a short time. However, at present, medical services still depend much on experience and intuition of a clinician. Therefore, even if a standard for making such a selection is given, it is often difficult to find out the basis on which the standard has been made.
Further, the results occurring from a selected treatment plan or the like varies from patient to patient, so that the results of the same treatment may vary from complete cure to failure depending on factors such as complication accompanying the treatment, side effects of pharmaceuticals, unsuccessful surgical operations and the like.
In deciding a treatment plan, the clinician must make a selection based on a more definite logical structure by clearly recognizing the possibility that each treatment may cause undesirable results with a certain probability. In order to solve this problem, EBM (Evidence Based Medicine) is proposed in which a suitable procedure (basically a randomized controlled trial) is taken to obtain results referred to as xe2x80x9cevidencexe2x80x9d and the decisions on the medical treatment plans or test plans are made based on the evidence.
EBM makes it possible to perform a statistically appropriate treatment based on objective data. Also, EBM is expected to contribute to reduction of medical expenses, such reduction being a worldwide trend in recent years.
At present, as evidence for EBM, there are individually descriptions of papers themselves, documents containing summaries of papers, and documents made into protocols. However, EBM has not reached a level such that the total circumstances are grasped by covering various clinical situations for practical clinical application.
Accordingly, a proposal is made in which complicated clinical situations are shown as a xe2x80x9cdecision treexe2x80x9d in a comprehensive manner by converting such evidence into protocols. According to this method, a decision tree is prepared to calculate expectations of nodes (branching points) on the decision tree based on occurrence probabilities of branches of the decision tree and utility values of leaves at terminal ends of the decision tree, whereby a node having the largest expectation is selected (See xe2x80x9cMedical Decision Sciences in the context of Clinical Pathologyxe2x80x9d, Tsuguya Fukui et al., 1991).
However, even if a lot of evidence is made into protocols, it is difficult to utilize these protocols effectively in clinical medicine due to various factors that fluctuate the evidence.
For example, due to the substantial development of treatment methods, inspection methods and the like in recent years, evidence that does not reflect this development may be totally unusable. Also, these treatment methods and test methods may vary depending on the institution in which they are used, so that the evidence may also vary from institution to institution. Moreover, simple statistical data of a total group of patients does not reflect the individual condition of each patient, such as the difference in age and sex, other diseases of the patient, the effects of pharmaceuticals and the like.
Therefore, it is difficult to use the evidence in clinical medicine unless the evidence reflects these factors.
Also, various medical decisions have previously been made using a simple criterion of life or death based on a survival rate. However, in recent years, such decisions must be made in accordance with various subjective senses of value of the patient on the health conditions occurring as a result of a treatment in view of QOL (quality of life).
For example, in a mastectomy for treating breast cancer, the selection of a treatment may vary depending on the sense of value of the patient on the mastectomy. The problem is how such a subjective sense of value of the patient can be incorporated in a process for making decisions such as selection of a medical treatment or test.
Furthermore, there is a trend that the decision power for selecting one of a plurality of treatment methods is transferred to the patient side after allowing the patient to fully understand the advantages and disadvantages of each of the treatment methods. This necessitates an xe2x80x9cinformed consentxe2x80x9d.
However, if a decision making support system using, for example, a neuro-network is adopted, there arises a problem that it is almost impossible to explain a decision making process to a patient because the decision making process is made into a black box.
The present invention has been made in view of these circumstances and the purpose thereof is to provide a system capable of (1) providing renewed evidence by successively introducing the latest data, (2) providing the optimal evidence for each patient, (3) supporting a flexible decision making process that meets the various needs (sense of values) of individual patients as well as providing statistically good medical services, (4) further supporting the xe2x80x9cinformed consentxe2x80x9d and (5) supporting the realization of highly efficient medical services in clinical medicine while allowing the system to be based on EBM and, more generally, a system for supporting human decision-making processes by creating a decision tree having a decision criterion that conforms best to the intended object in various situations.
Accordingly, the present invention provides a support system for making decisions on medical treatment plans or test plans, comprising using a decision tree including branches that represent actions to be selected in deciding the medical treatment plans or test plans for a person to be inspected and events that may possibly occur as a result of the selected actions, and calculating expectations of the actions to be selected in accordance with occurrence probabilities with which the respective events occur and utility values which reflect intentions of the person to be inspected on the events, wherein the occurrence probabilities of the branches are renewable in accordance with attribute information of the person to be inspected.